This invention relates to a spinning machine having several spinning stations for the spinning of slivers fed in cans into yarns, having guiding devices for the guiding of the slivers from the cans to drafting units pertaining to the spinning stations and having devices for protecting the slivers on their transport path.
It is known (British Patent Document GB 1 015 780) to feed slivers to a ring spinning machine in cans, withdraw them by way of rollers and then guide them to pairs of transport belts which receive the slivers between one another and transport them to the drafting units of the individual spinning stations. Transport belts of this type require high expenditures.
In the case of a ring spinning machine with package feeding, it is known (European Patent Document EP-0 041 484 B1) to guide the roving by way of a stationary spiral which is to provide a false twist to the roving and thus provide it with a higher strength.
Similar stationary false-twisting elements are also known in the case of roving frames (German Patent Document DE-OS 1 785 481) in which slivers are guided from cans to the drafting rollers.
In the older German Patent Application P 40 38 231.1, which is no prior publication, it was suggested to provide the slivers during the withdrawal from the cans with a true twist in that the cans are rotated about their axes.
It is an object of the invention to feed also finer slivers from cans, of a size range of from Nm 0.3 to 0.8, to a spinning machine, in which case these slivers are sufficiently protected on their transport path and, if possible, are no longer provided with a twist when entering into the drafting units, and the expenditures for protecting the slivers are as low as possible.
This object is achieved according to preferred embodiments of the invention in that false-twisting elements are provided as the devices for the protecting of the slivers which are connected directly in front of the drafting units.
During their transport path, the slivers are provided with a sufficient number of twists by means of the false-twisting elements so that they are strengthened to such an extent that they are protected against faulty drafts. Very long transport paths can be bridged in this manner. After leaving the false-twisting elements, thus when entering the drafting units pertaining to the spinning stations, the slivers will again be largely untwisted because, as is known, the false twist opens up again behind the false-twisting elements. However, the transport path between the false-twisting elements and the drafting units is only short and withstood by the slivers without suffering any damage. It is advantageous for the fibers of the slivers to again be directed in parallel when entering into the drafting units.
In a development of the invention, the guiding devices each have a deflecting guide which divides the transport path of the slivers into two essentially linear strands and to which a false-twisting element is also assigned. Such a deflecting guide makes it possible, for example, to deposit cans next to the spinning machine while leaving an operating aisle and to guide the slivers, in the manner of a roof, over the aisle to the spinning stations. The additional false-twisting element connected in front of the deflecting guide provides a sufficient protective twist also between the can and the deflecting guide because it cannot simply be assumed that the false twist running back from the false-twisting elements of the drafting units will propagate by way of the deflecting guides.
The false-twisting element assigned to the deflecting guide may be directly connected in front of the deflecting guide. However, as an alternative, it is also possible to design the false-twisting element itself as a deflecting guide. In this case, the false twisting element provides the sliver not only with the protective twist but is also used for the guiding of the sliver.
Expediently, the false-twisting elements are drivable. It is therefore possible to adapt the magnitude of the false twist to the respective fiber material.
Advantageously, feeding rollers situated in front of the pertaining false-twisting elements are connected in front of the drafting units, the delivery speed of the feeding rollers preferably being 5% lower than the feeding speed of the drafting unit. Thus, the circumstance is taken into account that the slivers are shortened as a result of the false twist and are lengthened again correspondingly behind the false twisting elements. When feeding rollers are present, it is therefore necessary to coordinate the speeds of the feeding rollers with the speeds of the feeding rollers of the drafting unit with respect to one another. Such a coordination does not present any problems technically but this aspect has to be taken into account.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.